The invention relates to an air-conditioning system for vehicles, of the generic type with a blower and an evaporator arranged downstream thereof and with a heat exchanger and an air distributor box which has air-outflow ports for at least one middle nozzle and for side nozzles and as appropriate for foot-space, back and deicer nozzles. The air distributor box is connected directly by means of its inlet cross-section to the evaporator and receives the heat exchanger approximately centrally in such a way that it is subdivided by the heat exchanger into a front space portion facing the evaporator and into a rear space portion located behind the heat exchanger. An air-guide connection piece branches off from the front space portion of an upper region of the air distributor box as seen from the evaporator, which connection piece carries the air-flow port for the middle nozzle at its end and of which at least one inflow port located in the air distributor box and extending over the entire evaporator width is selectively closeable by means of a cold-air scoop flap.
In a known air-conditioning system described in German Patent Document DE 3,542,626 A1, the heat exchanger is arranged at the entrance of the air distributor box. The air-outflow port for the deicer nozzle is provided in the upper region of the air distributor box, and air-outflow ports for side and foot-space nozzles are provided in the two lateral regions of the air distributor box. The air-outflow port for the middle nozzle is arranged at the end of a fresh-air channel divided into two separate branch lines which upstream are guided laterally past the heat exchanger on the left and right and which each terminate behind the evaporator in an air-inflow port. Downstream below the branch point, the fresh-air channel is connected to the air distributor box via a connecting port equipped with a mixer flap. A fresh-air regulating flap is arranged in each branch line. The desired temperature of the air flowing out at the middle nozzle can be set by adjusting the mixer flap and the fresh-air regulating flaps. A ventilation of the passenger space with fresh air, bypassing the heat exchanger, or a maximum cooling of the passenger space can be carried out only via the middle nozzle.
In a like wise known air-conditioning system of the type mentioned in the introduction and described in German Patent Document DE 3, 300,737 A1, the heat exchanger likewise arranged approximately centrally in the air distributor box covers the clear cross-section of the latter only partially and above the heat exchanger leaves free a bypass orifice which allows a direct flow of the cold air coming out of the evaporator into the rear space portion, bypassing the heat exchanger. The air fractions flowing through the heat exchanger and through the bypass orifice are adjusted by means of a regulating flap assigned to the bypass orifice. In the two extreme positions of the regulating flap, the bypass orifice and the heat exchanger are respectively covered completely, so that air flows solely through the heat exchanger (maximum heating mode) or solely through the bypass orifice (maximum cooling mode). The air fractions are mixed again in an air channel which connects the rear space portion to the middle nozzle and in which the foot-space and back nozzles are also arranged. The middle nozzle and foot-space and back nozzles are therefore always supplied with air at the same temperature. The cold-air scoop flap allows an additional direct feed of the middle nozzle with cold air, even in the heating mode, but with the exception of the "maximum heating" mode. It controls an air-through flow port which is arranged directly behind the bypass office and which connects the bypass orifice directly to the middle nozzle, bypassing the air channel extending from the rear space portion. By means of the cold-air scoop flap, in the middle nozzle cold air is mixed with the air stream of controlled temperature supplied to the middle nozzle via the air channel, thereby ensuring a better temperature stratification in the passenger space. A separate feed of the middle nozzle with cold-air only and of the back and foot-space nozzles with warm air only is not possible. For the "maximum cooling" mode, it is necessary to transfer the regulating flap into its end position covering the heat exchanger. Both the middle nozzle and the foot-space and back nozzles are then supplied with cold air. An additional opening of the cold-air scoop flap increases the fraction of cold air flowing to the middle nozzle.
An object on which the invention is based is to provide an air conditioning system of the type mentioned in the introduction, in which, without the need for a regulating flap for dividing the air stream into warm air and cold air, both the possibility of a separate supply of the middle nozzle with cold air or fresh air during the heating mode is afforded and, in the "maximum cooling" or "ventilation" mode, the supply of cold air or fresh air into the passenger space takes place via the middle nozzle and side nozzles, if appropriate also via the back and/or foot-space nozzles, for a more rapid cooling or ventilation of the passenger space.
In an air-conditioning system of the generic type indicated above, according to the invention the object is achieved by means of an arrangement wherein the heat exchanger completely covers the cross-section of the air distributor box, wherein there extends from the rear space portion of the air distributor box two bypass channels which are guided laterally around the heat exchanger and which terminate in the air-guide connection piece, wherein transition orifices of the bypass channels in the air-guide connection piece are selectively closeable by means of temperature control flaps, and wherein the air-outflow ports for the side nozzles are arranged in the two bypass channels.
With the installation according to the invention of the heat exchanger in the air distributor box, the design of the bypass channels leading past the heat exchanger from the rear space portion of the air distributor box to the air-guide connection piece above the cold-air scoop flap and the arrangement of the side nozzles in these bypass channels, in the heating mode the warm air is fed to the air-guide connection piece for the middle nozzle from the rear side of the heat exchanger via the bypass channels. Warm air passes both into the side nozzles and into the middle nozzle. By means of the temperature control flaps, an allocation of air quantity to the side nozzles and middle nozzle can be carried out. With the opening of the cold-air scoop flap, either cold air can be admixed for the middle nozzle (the temperature control flaps are open) or the middle nozzle is supplied only with cold air (the temperature control flaps are closed). In the "maximum cooling" or "ventilation" mode, the cold-air scoop flap is opened completely, with the temperature control flap open. The fresh or cold air flows out through the air-guide connection piece to the middle nozzle and, in the opposite direction to the warm air, through the bypass channels and comes out at the side nozzles. The air throughput is thereby increased and the desired cooler climate in the passenger space is obtained substantially more quickly.
If, according to one embodiment of the invention, the air-flow ports for the foot-space and back nozzles are likewise arranged in the lateral bypass channels and these are equipped with regulating flaps, then, if required, these nozzles too can be used for ventilating the passenger space in the "maximum cooling" and "ventilation" modes.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.